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| United States Patent |
5,162,858
|
|
Shoji
, et al.
|
November 10, 1992
|
Cleaning blade and apparatus employing the same
Abstract
The present invention provides a cleaning blade of a cleaning device for
eliminating remaining toner powder from a surface of an image-holding
member. The cleaning blade is constituted of silicone rubber. The silicone
rubber contains not more than 5% by weight of a low-viscosity
organosiloxane component, has rubber hardness within the range of from
40.degree. to 90.degree., and cause permanent compression set of not more
than 20% according to JIS A.
| Inventors:
|
Shoji; Takeo (Yokohama, JP);
Sasame; Hiroshi (Yokohama, JP);
Adachi; Hiroyuki (Tokyo, JP);
Watabe; Masahiro (Yokohama, JP);
Yanai; Noriyuki (Yokohama, JP)
|
| Assignee:
|
Canon Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
634705 |
| Filed:
|
December 27, 1990 |
Foreign Application Priority Data
| Current U.S. Class: |
399/350 |
| Intern'l Class: |
G03G 021/00 |
| Field of Search: |
355/296,297,298,299
118/652
|
References Cited
U.S. Patent Documents
| 3752576 | Aug., 1973 | Gerbasi | 355/297.
|
| 3980494 | Sep., 1976 | Beatty et al. | 355/299.
|
| 4440488 | Apr., 1984 | Maekawa et al.
| |
| 4825249 | Apr., 1989 | Oki et al. | 355/299.
|
| 4830893 | May., 1989 | Nakamura et al. | 428/35.
|
| Foreign Patent Documents |
| 384354 | Aug., 1990 | EP.
| |
| 61-63877 | Apr., 1986 | JP.
| |
Primary Examiner: Braun; Fred L.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper & Scinto
Claims
What is claimed is:
1. A cleaning blade of a cleaning device for eliminating remaining toner
powder from a surface of an image-holding member, said cleaning blade
being constituted of silicone rubber, and said silicone rubber;
(a) containing not more than 5% by weight of a low-viscosity organosiloxane
component,
(b) having a rubber hardness within the range of from 40.degree. to
90.degree., and
(c) exhibiting a permanent compression set of not more than 20% according
to JIS A, wherein the silicone rubber of the cleaning blade contains a
silica filler having a particle diameter of not more than 1.mu..
2. The cleaning blade of claim 1, wherein the silica has been treated for
hydrophobicity.
3. The cleaning blade of claim 1, wherein a supporting member of holding
the cleaning blade is placed in a mold for molding the cleaning blade, and
the cleaning blade is molded with the supporting member in one body by
injection molding.
4. The cleaning blade of claim 1, wherein the cleaning blade is formed from
an addition reaction type of liquid silicone rubber.
5. An apparatus unit mountable to and demountable from a main apparatus,
said unit being constructed from at least one of a charging means and a
developing means, together with a cleaning blade in one unit, said
cleaning blade being constituted of silicone rubber, and said silicone
rubber:
(a) containing not more than 5% by weight of a low-viscosity organosiloxane
component,
(b) having a rubber hardness within the range of from 40.degree. to
90.degree., and
(c) exhibiting a permanent compression set of not more than 20% according
to JIS A, wherein the silicone rubber of the cleaning blade contains a
silica filler having a particle diameter of not more than 1.mu..
6. An electrophotographic apparatus comprising:
(a) a photosensitive member,
(b) a latent image forming member,
(c) a developing means for developing a formed latent image,
(d) a transfer means for transferring a developed image onto a
transfer-receiving material, and
(e) a cleaning blade,
said cleaning blade being constituted of silicone rubber, said silicone
rubber:
(1) containing not more than 5% by weight of a low-viscosity organosiloxane
component,
(2) having a rubber hardness within the range of from 40.degree. to
90.degree., and
(3) exhibiting a permanent compression set of not more than 20% according
to JIS A,
wherein the silicone rubber of the cleaning blade contains a silica filler
having a particle diameter of not more than 1.mu.. .mu..
7. A facsimile apparatus comprising:
(a) an electrophotographic apparatus and
(b) receiving means for receiving an image information from a remote
terminal,
said electrophotographic apparatus comprising:
(1) a photosensitive member,
(2) a latent image forming member,
(3) a developing means for developing a formed latent image,
(4) a transfer means for transferring a developed image onto a
transfer-receiving material, and
(5) a cleaning blade,
said cleaning blade being constituted of silicone rubber, said silicone
rubber:
(i) containing not more than 5% by weight of a low-viscosity organosiloxane
component,
(ii) having a rubber hardness within the range of from 40.degree. to
90.degree., and
(iii) exhibiting a permanent compression set of not more than 20% according
to JIS A,
wherein the silicone rubber of the cleaning blade contains a silica filler
having a particle diameter of not more than 1.mu..
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cleaning blade that is employed in a
cleaning device of an image forming apparatus, such as electrostatic
copying machines, printers, and facsimile apparatuses, and is used for
eliminating remaining toner from a surface of an image-holding member by
pressure-contact thereto.
The present invention also relates to an apparatus employing the cleaning
blade.
2. Related Background Art
In a known image forming apparatus, in which transferable toner images
formed on an image-holding member are repeatedly transferred onto a
transfer material, such as paper, the toner remaining on an image-holding
member has to be removed completely in every transfer step. Generally the
remaining toner is eliminated by pressing uniformly against the surface of
the image-holding member a blade, which is made of a rubber elastomer and
has a precise edge, against the surface of the image-holding member and
sliding the blade on the surface. The cleaning blade is usually made of
urethane rubber.
The cleaning process employing the urethane rubber, however, is
disadvantageous in that the simple pressure-contact of the cleaning blade
with the image-holding member causes reversal or bounding of the cleaning
blade 3 of urethane rubber, which supported by supporting member 2 as
shown by a dotted line in FIG. 1. The reversal or bounding is caused by
the high friction coefficient of the urethane rubber material, which
results in strong friction between the urethane rubber and the
image-holding member. Thus, the remaining toner is not completely removed.
For this reason, various measures have been investigated and tired. For
example, the tip of the cleaning blade made of polyurethane rubber or the
surface of the photosensitive member may be covered with a lubricating
fine powder or the like of a fluorine type resin, such as polyvinylidene
fluoride and polytetrafluoroethylene, to reduce the amount of friction
between the urethane rubber and the photosensitive member at an initial
sliding stage. Such lubricating fine powder must be applied uniformly in a
minimum amount since excessive application deleteriously affects the image
due to its electric characteristics. However, such application is not easy
technically, and still involves reliability problems with respect to the
reversal or bounding of the blade caused by non-uniform coating.
Another problem is that, during repetition of the cleaning process, the
lubricating fine powder maybe scattered and lost from the vicinity of the
edge, thus reducing its lubricating effect. The toner, which then comes
instead to play the role of the lubricating powder instead, provides a
less friction-reducing effect. As a result the urethane blade tends to
scatch or abrade the photosensitive member and shorten the life thereof,
especially when the photosensitive member is an organic
photosemiconductor.
Morever, when a urethane rubber material is used for such a cleaning blade,
a casting type thermosetting liquid urethane is usually used to prepare
the blade because of abrasion resistance of this material with respect to
the photosensitive member. Further, this type of material is less likely
to contaminate the photosensitive member, the toner and the like as a
result release by the urethane rubber of an exudate. This type of urethane
material, however, requires a long reaction time for heat cure, and is
highly reactive to moisture in the atmosphere, thus involving problems in
production equipment cost, and control of the material quality.
Accordingly, a production process free from such problems are desired.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a cleaning blade having a
small friction coefficient, which will not scratch the surface of an
image-holding member.
Another object of the present invention is to provide a cleaning blade
which is readily produced with uniform quality.
A further object of the present invention is to provide an apparatus
equipped with an image-holding member.
According to one aspect of the present invention, there is provided a
cleaning device having a cleaning blade eliminates toner power remaining
on a surface of an image-holding member. The cleaning blade is constituted
of silcone rubber, and the silicone rubber contains not more than 5% by
weight of a low-viscosity organosiloxane component, has a rubber hardness
within the range of from 40.degree. to 90.degree., and exhibits a
permanent compression set of not more than 20% according to JIS A.
According to another aspect of the present invention, there is provided an
apparatus unit mountable to and demountable from a main apparatus, the
unit being constructed from (1) at least one of a charging means and a
developing means and (2) a cleaning blade in one unit. The cleaning blade
is constituted of silicone rubber, and the silicone rubber contains not
more than 5% by weight of a low-viscosity organosiloxane component, has
rubber hardness within the range of from 40.degree. to 90.degree., and
exhibits a permanent compression set of not more than 20% according to JIS
A.
According to still another aspect of the present invention, there is
provided an electrophotographic apparatus comprising a photosensitive
member, a latent image forming member, a developing means for developing a
formed latent image, a transfer means for transferring a developed image
onto a transfer-receiving material, and a cleaning blade. The cleaning
blade is constituted of silicone rubber, and the silicone rubber contains
not more than 5% by weight of a low-viscosity organosiloxane component,
has a rubber hardness within the range of from 40.degree. to 90.degree.,
and exhibits a permanent compression set of not more than 20% according to
JIS A.
According to a further aspect of the present invention, there is provided a
facsimile apparatus comprising an electrophotographic apparatus and
receiving means for receiving image information from a remote terminal.
The electrophotographic apparatus comprises a photosensitive member, a
latent image forming member, a developing means for developing a formed
latent image, a transfer means for transferring a developed image onto a
transfer-receiving material, and a cleaning blade. The cleaning blade is
constituted of silicone rubber, and the silicone rubber contains not more
than 5% by weight of a low-viscosity organosiloxane component, has a
rubber hardness within the range of from 40.degree. to 90.degree., and
exhibits a permanent compression set of not more than 20% according to JIS
A.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates reversal of a cleaning blade.
FIG. 2 is an enlarged illustration of a sliding portion of a cleaning blade
brought into contact with a photosensitive member drum.
FIG. 3 illustrates roughly the constitution of a usual transfer-type of
electrophotographic apparatus employing a cleaning blade of the present
invention.
FIG. 4 is a block diagram of a facsimile apparatus employing, as a printer,
an electrophotographic apparatus having a cleaning blade of the present
invention.
FIG. 5 illustrates a state of abrasion of a cleaning blade after use for a
long period.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The cleaning blade of the present invention has a small friction
coefficient, and is abraded by itself gradually as shown in FIG. 2 into
fine powder 5 without scratching the surface of a photosensitive member
drum 1. The resulting minor amount of the powder functions as a
lubricating medium, allowing toner 4 to be eliminated with low friction
sliding. The cleaning blade is produced by a technique of rubber injection
molding and therefore is simple and reliable to make.
The cleaning blade of the present invention does not undergo reversal of
the blade at the initial stage of sliding on a photosensitive member,
lengthens the life of an image-holding member, such as a photosensitive
member, without scratching thereof, and is efficiently with high quality,
thus giving satisfactory cleaning performance.
The silicone rubber used to make the cleaning blade of the invention is
designed to provide sufficient contact pressure to remove the remaining
toner. The rubber hardness is tested by pressing it to an image-holding
member from a distance larger than a predetermined distance and with a
load that is larger than a predetermined load. A rubber hardness that is
too low causes insufficiency of the pressure or elasticity of the rubber,
which causes the cleaning blade to come into contact with an image-holding
member through a larger than desirable surface, thus increasing friction
and decreasing the sliding ability. Therefore, the hardness is preferably
not less than 40.degree. according to JIS A. A cleaning member having a
higher hardness can cause scratching on the image-holding member.
Therefore, the hardness is preferably not higher than 90.degree. according
to JIS A. More preferably, the hardness is within the range of from
50.degree. to 80.degree. according to JIS A.
The contact pressure of the cleaning member to the image-holding member has
to be maintained at a pressure higher than a predetermined minimum
variation in the pressure since, at a pressure lower than the minimum, the
elimination of the remaining toner will become impracticable. On receiving
a contact pressure, rubbers can deform irreversibly by internal plastic
flow, namely creeping. The cleaning member desirably causes less creeping.
As a criterion, the permanent compression set of the rubber is preferably
not more than 20%, more preferably not more than 10%.
Silicone rubbers usually contain a low-molecular-weight polysiloxane oil
having a low viscosity of about 20 centipoise or less, which has been
formed from raw materials typically used for the synthesis of silicone
rubbers. At a higher content of this component, contact-pressing the edge
of a silicone rubber cleaning blade, the pressure onto the surface can
reach several tens of kg/cm.sup.2, which causes the exuding of a
low-viscosity oil onto the surface of the image-holding member, thereby
adversely affecting the electrostatic photographic process. Therefore the
silicone rubber used for the invention preferably contains a smaller
amount of the low-viscosity oil component, preferably not higher than 5%
by weight, more preferably not more than 3% by weight.
The silicone rubber is of any material of a room temperature-curable type
of RTV, a low temperature-curable type of LTV, a high temperature-curable
type of HTV, and the like, provided that it satisfies the aforementioned
requirements. However, the LTV, an addition reaction-type liquid silicone
rubbers, is preferable because it has a sufficient rubber flow property,
reacts quickly by heating, leaves no unreacted matter, and exhibits
relatively little molding shrinkage.
For the purpose of imparting a minimum level of abrasion resistance, a
filler having primary particles with a small average diameter is added to
the silicone rubber used to form the cleaning blade. If the particle
diameter is larger than that of the toner particles employed in the an
electrophotographic apparatus, problems can arises because the filler
particles rougher the edge portion formed on the cleaning blade made from
silicone rubber containing the dispersed filler particles. When the
roughened edge comes into pressure-contact with the image-holding member
the toner cleaning can become impracticable. The cleaning performance is
further lowered as because the abraded and chipped portions of the
silicone rubber cleaning blade becomes larger in diameter than the toner
particles. Accordingly, the filler preferably has a diameter less than
that of the toner, and more preferably, a diameter of not larger than 1
micron. The filler to be added is preferably in an amount of not less than
5% by weight in view of viscoelastic mechanical property, of the material,
the degree of abrasion imparted, and the length of time by which the life
of the silicone rubber cleaning blade is lengthened.
The filler to be added may be any material, provided that the
aforementioned property requirements are satisfied. The examples include
fine organic resin powder, such as ultra-high density polyethylene, nylon,
and fluorine-type resins, and fine inorganic powder such as molybdenum
disulfide, fluorocarbon, and silica, and multi-component systems derived
therefrom. Among them, fine powder silica including wet-process silica and
dry-process silica is preferred in view of the particle diameter, the
dispersibility in silicone rubber, and the lack of scratching of the
surface of an image-holding member. In particular, hydrophobicity-treated
silica, which has improved dispersibility, is preferable. Further, fumed
silica and hydrophobicity-treated fumed silica are preferred in view of
the particle diameter.
In the cleaning process, the cleaning blade is required to be brought into
precise contact with a curved surface of a cylindrical photosensitive drum
or the like to achieve satisfactory cleaning performance, for which the
cleaning blade itself must be dimensionally precise. For this purpose, the
cleaning blade is most desirably molded by injection molding, using a mold
that is dimensionally highly precise and clamping at high pressure. The
dimensional precision is thereby improved, and the injection reaction time
is shortened due to the high shear flow of the rubber at injection, which
is advantageous in production.
Because the bonding of the molded silicone rubber with a supporting member
is liable to be insufficient a supporting member, which has preliminarily
had an adhesive applied on the portion to be bonded, is inserted into the
mold, prior to molding. In this way, silicone rubber is molded in
integrity with the supporting member, thus attaining strong bonding by
utilizing the rubber formation reaction. In such a manner, a cleaning
blade having a higher quality is prepared in a shorter molding time, as
compared with the one made of urethane rubber.
FIG. 3 illustrates roughly a constitution of the usual transfer-type of
electrophotographic apparatus employing a drum-shaped photosensitive
member.
In FIG. 3, a drum-shaped photosensitive member 11 as an image-holding
member is driven to rotate around an axis 11a in an arrow direction at a
predetermined peripheral velocity. During the rotation, the photosensitive
member 11 is electrified uniformly to a predetermined positive or negative
potential with an electrifying means 12 and, subsequently, is exposed to a
light image projection L from a light image projection means not shown in
the figure (slit exposure, laser beam-scanning exposure, etc.) at an
exposure section 13. Thereby electrostatic laten images are successively
formed on the peripheral surface of the photosensitive member in
correspondence with the projected image.
The electrostatic latent image is subsequently subjected to toner
developement with a developing means 14, and the developed toner image is
successively transferred by a transfer means 15 onto the surface of a
transfer-receiving material P which is fed synchronously with the rotation
of the photosensitive member 11 to the space between the photosensitive
member 11 and the transfer means 15 from a paper-feeding portion not shown
in the figure.
The transfer-receiving material P, having received the transferred image,
is separated from the surface of the photosensitive member and introduced
into an image-fixing means 18 to have the image fixed, and is then sent
out of the apparatus as a copied material.
After the image transfer, the surface of the photosensitive member 11 after
the image transfer is cleaned to removal the remaining toner by using a
cleaning blade 16 of the present invention, is treated with a preliminary
exposure means 17 to erase electrostatic charge, and then used repeatedly
for image formation.
The uniform electrifying means 12 generally used for the photosensitive
member 11 is a corona electrifying apparatus. The transfer means 15
generally used is also a corona electrifying means. In the
electrophotographic apparatus, out of the structural elements such as a
photosensitive member, a developing means, and a cleaning means, a
plurality of the units may be integrated into one apparatus unit so that
the apparatus unit may be mountable to and demountable from the main body
of the apparatus. For example, at least one of the electrifying means and
the developing means can be integrated with the photosensitive member and
the cleaning blade into one unit which is mountable and demountable by a
guiding means such as a rail in the main body of the apparatus. The
aforementioned apparatus unit may comprise an electrifying means and/or a
developing means.
In the case where the electrophotographic apparatus is used as a copying
machine or a printer, the light image projection L is given as reflected
light or transmitted light from an original copy, or otherwise given by
the scanning of a laser beam, the driving of an LED array, or the driving
of a liquid crystal shutter array, in accordance with the signal made by a
read-out of an original copy.
In the case where the electrophotographic apparatus is used as a printer of
a facsimile apparatus, the light image projection L is conducted for
printing out the received data. FIG. 4 shows a block diagram of an example
for such a case.
A controller 21 controls an image reading section 20 and a printer 29. The
whole of the controller 21 is controlled by CPU 27. The read-out data from
the image reading section is transmitted to the other communication party
through a transmitting circuit 23. Data received from the other
communication party is sent through a receiving circuit 22 to the printer
29. The image data is stored in an image memory. A printer controller 28
controls a printer 29. The numeral 24 denotes a telephone.
An image received through a circuit 25 (image information from a remote
terminal connected through the circuit), after demodulated with the
receiving circuit 22, decoded by CPU 27 and successively stored in the
image memory 26. When at least one page of an image have been stored in
the image memory 26, the recording of the image of the page is conducted.
The CPU 27 reads out one page of image information from the image memory
26, and sends out the decoded one page of image information to the printer
controller 28, which controls a printer 29 so as to record the one page of
image information on receiving it from CPU 27.
The CPU 27 receives the following page during the recording by the printer
29.
Images are continuously received and recorded in a manner as described
above.
Method for Preparing Cleaning Blade
Liquid A of TSE 3032 (trade name, made by Toshiba Silicone K.K.), which
contains a polysiloxane oil having a terminal vinyl group, a platinum type
catalyst, and silica, and Liquid B of TSE 3032, which contains a
polysiloxane oil having a terminal vinyl group, a reaction controlling
agent, a hydrosilane, and silica were employed.
The mixing ratio of Liquid A and Liquid B, the content of silica in each
Liquid, and the particle diameter of the silica were adjusted so as to
obtain the molded cleaning blade having the hardnesses shown in Table 1.
The starting material mixture formulated as above was injection-molded into
a mold heated preliminarily to 170.degree. C. and having a supporting
member inserted therein, which had been treated for adhesion with a
vulcanizing adhesive. After 60 seconds from the injection, the molded
blade was removed from the mold, and was subjected to secondary cure at
200.degree. C. for 4 hours. Subsequently, the blade was subjected to edge
formation. The resulting article was used as a cleaning blade.
The cleaning blade formed above was evaluated for reversal at the initial
sliding, degree of scratching of the surface of the photosensitive member
after 3000 sheets of paper had passed, and the cleanability by use of an
electrophotographic copying machine (Personal Copia FC-5, trade name, made
by Canon K.K.) employing an organic photosensitive member.
EXAMPLE 1
The main material and curing material were prepared by dispersing therein
the following amount of silica.
Main Material
______________________________________
TSE 3032A 100 g
(Two liquid addition reaction-type silicones
manufactured by Toshiba Silicone)
RX-200 (primary particle size: 14 .mu.m)
10 g
(Hydrohobicity-treated fumed silica
manufactured by Japan Aerosil)
______________________________________
Curing Material
______________________________________
TSE3032B 10 g
RX-200 1 g
______________________________________
Conditions of Molding
A supporting member, which had been pre-treated with vulcanizable adhesive
for adhesion, was inserted in an injection molding machine. The main
material and the curing material were mixed in a ratio of 10:1 and molded
by using the injection molding machine. The molded product was worked into
a predetermined shape.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 sec
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
______________________________________
Properties of the Molded Article
______________________________________
Rubber hardness JIS A 56.degree.
Permanent compression set (70.degree. C.)
7%
______________________________________
EXAMPLE 2
The main material and curing material were prepared by dispersing therein
the following amount of silica.
Main Material
______________________________________
TSE 3032A 100 g
(Two liquid addition-reaction type silicones
manufactured by Toshiba Silicone)
RX-200 (primary particle size: 14 .mu.m)
20 g
(Hydrohobicity-treated fumed silica
manufactured by Japan Aerosil)
______________________________________
Curing Material
______________________________________
TSE3032B
10 g
RX-200 2 g
______________________________________
Conditions of Molding
A supporting member, which had been pre-treated with vulcanizable adhesive,
for adhesion was inserted in an injection molding machine. The main
material and the curing material were mixed in a ratio of 10:1 and molded
by using the injection molding machine. The molded product was worked into
a predetermined shape.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 sec
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
______________________________________
Properties of the Molded Article
______________________________________
Rubber hardness JIS A 66.degree.
Permanent compression set (70.degree. C.)
7%
______________________________________
EXAMPLE 3
The main material and curing material were prepared by dispersing therein
the following amount of silica.
Main material
______________________________________
TSE 3032A 100 g
(Two liquid addition-reaction type silicones
manufactured by Toshiba Silicone)
RX-200 (primary particle size: 14 .mu.m)
10 g
(Hydrohobicity-treated fumed silica
manufactured by Japan Aerosil)
______________________________________
Curing Material
______________________________________
TSE3032B 10 g
RX-200 1 g
______________________________________
Conditions of Molding
A supporting member, which had been pre-treated with vulcanizable adhesive,
for adhesion was inserted in an injection molding machine. The main
material and the curing material were mixed in a ratio of 10:3 and molded
by using the injection molding machine. The molded product was worked into
a predetermined shape.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 sec
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
______________________________________
Propereties of the molded article
______________________________________
Rubber hardness JIS A 76.degree.
Permanent compression set (70.degree. C.)
6%
______________________________________
EXAMPLE 4
The main material and curing material were prepared by dispersing therein
the following amount of silica.
Main Material
______________________________________
TSE 3032A 100 g
(Two liquid addition-reaction type silicones
manufactured by Toshiba Silicone)
RX-200 (primary particle size: 14 .mu.m)
10 g
(Hydrohobicity-treated fumed silica
manufactured by Japan Aerosil)
______________________________________
Curing Material
______________________________________
TSE3032B 10 g
RX-200 1 g
______________________________________
Conditions of Molding
A supporting member, which had been pre-treated with vulcanizable adhesive
for adhesion, was inserted in an injection molding machine. The main
material and the curing material were mixed in a ratio of 10:0.7 and
molded by using the injection molding machine. The molded product was
worked into a predetermined shape.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 sec
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
______________________________________
Properties of the Molded Article
______________________________________
Rubber hardness JIS A 46.degree.
Permanent compression set (70.degree. C.)
8%
______________________________________
EXAMPLE 5
The main material and curing material were prepared by dispersing therein
the following amount of silica.
Main material
______________________________________
TSE 3032A 100 g
(Two liquid addition-reaction type silicones
manufactured by Toshiba Silicone)
Tokusil u (primary particle size: 20 .mu.m)
10 g
(Trade name; Wet-process silica
manufactured by Tokuyama Soda)
______________________________________
Curing Material
______________________________________
TSE3032B 10 g
RX-200 1 g
______________________________________
Conditions of Molding
A supporting member, which had been pre-treated with vulcanizable adhesive
for adhesion, was inserted in an injection the molding machine. The main
material and the curing material were mixed in a ratio of 10:1 and molded
by using the injection molding machine. The molded product was worked into
a predetermined shape.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 sec
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
______________________________________
Properties of the Molded Article
______________________________________
Rubber hardness JIS A 56.degree.
Permanent compression set (70.degree. C.)
9%
______________________________________
COMPARATIVE EXAMPLE 1
Rubber Material
______________________________________
Ethylene adipate-type urethane prepolymer
100 gr
(made by Nippon Polyurethane Kogyo K.K.;
Mn: 1500, NCO: 6.2% by weight)
______________________________________
Curing Agent
______________________________________
1,4-butanediol 3.9 gr
Trimethylolpropane 2.1 gr
Molding temperature 130.degree.
C.
Molding time 30 minutes
Secondary curing temperature
130.degree.
C.
Secondary curing time 4 hours
______________________________________
The urethane prepolymer was melted by heating, and the curing agent was
mixed therewith. The mixture was cast in a heated mold and was heat-cured.
The molded product was worked into a predetermined shape.
Properties of the Molded Article
______________________________________
Rubber hardness: JIS A 62.degree.
Permanent compression set (70.degree. C.):
9%
______________________________________
COMPARATIVE EXAMPLE 2
The experiment was conducted in the same manner as in Example 1 except that
aluminum silicate, Kyoritsu Hard Clay H-1 (trade name, made by Kyoritsu
Yogyo K.K. ), was used in place of the silica.
COMPARATIVE EXAMPLE 3
Silicone Rubber Material
Commercial grades of a main material and a curing material, each containing
silica and an other filler dispersed therein,
______________________________________
TSE 1026, Main material A 100 gr
(two-part addition-type liquid silicone,
made by Toshiba Silicone K.K.)
TSE 1026, Curing material B
100 gr
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Molding Conditions
The main material and the curing material were combined in a ratio of 1:1
and were molded, injection molding by using a mold having a supporting
member inserted therein which had preliminarily been treated for adhesion.
The molded material was then subjected to secondary curing, and worked for
edge formation, thus providing a cleaning blade.
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Molding temperature 170.degree.
C.
Molding time 60 seconds
Secondary curing temperature
200.degree.
C.
Secondary curing time 4 hours
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Properties of Molded Article
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Rubber hardness: JIS A 62.degree.
Permanent compression set (70.degree. C.):
12%
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COMPARATIVE EXAMPLE 4
Silicone Rubber Material
Commercial grades of a main material and a curing material, each containing
silica and another filler dispersed therein,
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TSE 1026, Main material A 100 gr
(two-part addition type liquid silicone,
made by Toshiba Silicone K.K.)
TSE 1026, Curing material B
100 gr
______________________________________
Molding Conditions
The main material and the curing material were combined in a ratio of 1:1
and molded, injection molding by using a mold having a supporting member
inserted therein which had been preliminarily treated for adhesion. The
molded material was then worked for edge formation, thus providing a
cleaning blade.
______________________________________
Molding temperature 170.degree.
C.
Molding time 60 seconds
______________________________________
______________________________________
Rubber hardness: JIS A 58.degree.
Permanent compression set. (70.degree. C.):
30%
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The cleaning blade formed above was evaluated for reversal at the initial
sliding stage, the degree of scratching of the surface of the
photosensitive member after 3000 sheets of paper had passed, and the
cleanability by using an electrophotographic copying machine (Personal
Copia FC-5, trade name, made by Canon K.K.) employing an organic
photosensitive member.
TABLE 1
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Example Comparative example
1 2 3 4 5 1 2 3 4
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Kind of rubber
Silicone
Silicone
Silicone
Silicone
Silicone
Urethane
Silicone
Silicone
Silicone
Particle size
14 14 14 14 20 -- 2000 Mixture
Mixture
of silica (.mu.m)
Amount of silica
10 20 10 10 10 -- 10
(% by weight)
Rubber hard-
56 66 76 46 56 62 60 60 60
ness (JIS A)
Permanent com-
7 7 6 8 9 9 12 12 30
pression set (%)
Oil content
3 2.6 3 3 3 -- 3 12 15
(% by weight)
Reversal at
O O O O O X O O O
initial stage
Scratch of photo-
no no no no no yes yes yes --
sensitive member
Cleanability
good good good good good good poor poor poor
Oil exudation
no no no no no no no yes yes
Abrasion (.mu.m.sup.2)
50 25 38 75 60 0 1000 800 --
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REMARKS
1) Oil content: 5 grams of the rubber sample was cut into small pieces and
was extracted with 100 cc of hexane by means of a Soxhlet extractor for 20
hours. The hexane was then evaporated off, and the weight of the remaining
extract was represented in % by weight.
2) Reversal at initial sliding stage: The symbol O denote that no reversal
was observed, and the symbol X denotes that reversal was observed.
In the case of the urethane blade, when vinylidene fluoride powder is
applied at the tip of the blade, no reversal occurs, but, when it is not
applied, reversal occurs. Accordingly, the test for scratching of the
photosensitive member, cleanability, and oil exudation was conducted with
application of the powder.
3) Scratching of photosensitive member: In image printing at an optimum
density level with a Canon Family Copia FC-5 (trade name), the scratching
of the photosensitive member is evaluated as "yes" when a black line is
observed in the photosensitive drum periphery direction, and otherwise
evaluated as "no".
4) Cleanability: In image printing in the same manner as described in the
above item 3), the cleanability is evaluated as "poor" when a black line
is observed in the photosensitive drum periphery direction and further
toner remains on the photosensitive member after cleaning, evaluated as
"good", and when no black line is observed.
5) Oil exudation: In image printing in the same manner as described in the
above item 3) , oil exudation is evaluated as "yes" when a black line is
observed on the photosensitive member at a pressure-contacting position of
the cleaning blade in a length direction of the drum. Oil exudation is
evaluated as "no" when no black line is observed.
6) Permanent compression set: Measured according to JIS K 6301.
7) Particle diameter; Denoted by the average diameter in m.mu. of primary
particles, as measured by electromicroscopy.
8) Abrasion: represented by the area (.mu.m.sup.2) of the abraded portion 6
of the abraded blade 3, as shown in FIG. 5.
As is clear from the above results, all of the cleaning blades of Examples
1 to 5 of the present invention were found to undergo no reversal at the
initial sliding stage, to have excellent cleanability, and to cause no oil
exudation.
In comparison, the cleaning blade of Comparative example 1 undergoes
reversal in the absence of fine powder of vinylidene fluoride, but it also
scratches the photosensitive member in the presence of the fine powder
added, thus shortening the life of the photosensitive member. The cleaning
blade of Comparative example 2, scratches the photosensitive member and
has low cleanability owing to the large particle size of the filler, which
give an inferior image. The cleaning blade of Comparative example 3 has an
edge roughness of several .mu. to ten or more .mu. after edge working,
which is unsatisfactory both in scratching of the photosensitive member
and in cleanability, and additionally causes oil exudation owing to a
larger oil content. The cleaning blade of Comparative example 4 is made of
the same rubber as that of Comparative example 3, but is not subjected to
the secondary curing, which causes a larger permanent compression set,
thus resulting in poor cleaning after 200 to 300 sheets of printing.
Further, comparative example 4 involves a problem of oil exudation owing
to a high oil content.
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